JP2022075529A - Magnets in electrical machines - Google Patents

Abstract

To provide: electrical machines, and more specifically, electrical machines including permanent magnets; wind turbines comprising such electrical machines, and in particular, wind turbines comprising permanent magnet generators with cooling arrangements.SOLUTION: The present disclosure relates to rotors for an electrical machine comprising a first type of permanent magnets and a second type of permanent magnets, where the first and second types of permanent magnets have the same magnetic strength, and where the first type of permanent magnets has a first temperature rating, and the second type of permanent magnets has a second temperature rating different from the first temperature rating. The present disclosure relates to generators, and in particular to wind turbines comprising such generators, and to methods for selecting or providing magnets for permanent magnet rotors.SELECTED DRAWING: Figure 3

Description

The present disclosure relates to electrical machinery, and more particularly to electrical machinery including permanent magnets. The present disclosure also relates to wind turbines with such electrical machinery, and in particular to wind turbines with permanent magnet generators having a cooling arrangement configuration.

Electrical machines such as motors and generators generally include a rotor structure and a stator structure. The large generator may be, for example, a permanent magnet excitation generator (PMG).

Such generators can be used, for example, in wind turbines. Wind turbines typically include a rotor hub and a rotor with multiple blades. The rotor is set to rotate under the influence of wind on the blades. Rotation of the rotor shaft drives the generator rotor directly (“direct drive”) or using a gearbox. Such directly driven wind turbine generators can have a diameter of, for example, 6-10 meters (236-328 inches), such as a length of 2-3 meters (79-118 inches), eg, 2-20 rpm. It can rotate at low speeds in the range of (rotation per minute). Alternatively, the permanent magnet generator may also be coupled to a gearbox that increases the rotational speed of the generator to, for example, 50-500 rpm or higher.

The electromechanical machine comprises a rotor that rotates with respect to the stator. The rotor may have an inner structure and the stator may have an outer structure. Therefore, the stator in this case surrounds the rotor. Alternatively, the configuration may be the opposite: a rotor may surround the stator.

In the case of permanent magnet excitation generators (PMGs), permanent magnets (PMs) are generally provided in the rotor (although they can be arranged alternately in the stator structure), but winding elements (eg coils) are usually included in the stator. (However, it can be arranged alternately in the rotor structure). Permanent magnet generators are generally considered reliable and require less maintenance than other generator types. This is an important reason why permanent magnet generators are used in offshore wind turbines, especially directly driven offshore wind turbines.

A plurality of permanent magnets may be provided in the permanent magnet module, and these may be attached to the rotor as a single component. A permanent magnet module may be defined as a unit having a plurality of permanent magnets, and the plurality of magnets can be mounted and removed together. Such a module may have a module base having a shape suitable for accommodating or supporting a plurality of permanent magnets that may be secured to the base. The base may be configured to be secured to the rotor rim such that the plurality of magnets are anchored together to the rotor rim through the module base. The use of permanent magnet modules can facilitate the manufacture of rotors.

Cooling is generally important in electrical machinery because active elements (magnets or coils) generate heat during use. If the temperature is too high, it can lead to failure of these elements and reduced operating efficiency.

Different configurations of electromechanical machines, such as radial and axial machines, are known. In an axial machine, the rotor and stator face each other axially. An air gap is arranged axially between the rotor and the stator. In radial machines, a substantially annular air gap may be formed between the rotor and the stator. One of the rotor and the stator is arranged so as to surround the other in the radial direction. The movement of the rotor causes the air in the air gap to move around. This allows the air to provide a cooling effect, especially in the case of high speed rotation.

It is known to provide an active air cooling system or air conditioning system that provides a low temperature air flow through an inner stator structure. The cooling air flow is then distributed along the circumference of the stator. The airflow then axially traverses the air gap from one side to the other to cool the active elements of the rotor and stator. The hot air is then collected on the opposite axial side. The hot air is then exhausted or cooled in the heat exchanger and can be used again. This type of cooling, in which the cooling air crosses the radial air gap axially, is commonly referred to as axial cooling.

Radial cooling is also known, in which cooling air is blown radially into the radial air gap at various points, usually along the axial length of the rotor. Axial cooling is generally preferred for axially short electrical machines, and radial cooling is often preferred for axially long electrical machines.

As the cooling air crosses the air gap axially from one side to the other, the air is heated as it passes through the air gap. Therefore, the cooling air is cooler on one side than on the other side, thus cooling one side more effectively than the other. As a result, the cooling of the active element may not be uniform, i.e. the magnet on one side of the rotor may be at a higher temperature than the magnet on the other side.

Non-uniform temperature distribution between magnets can affect the operation of electromechanical machines. Degaussing is the process by which permanent magnets lose their magnetic properties. Demagnetization occurs in the presence of a strong magnetic field, eg, a magnetic field caused by a stator current, especially a fault current in an electromechanical machine. Therefore, degaussing of permanent magnets can occur during use and over the life of the electrical machine, and degaussing occurs more quickly and to a greater extent at high temperatures.

If the temperature distribution is non-uniform in the axial direction as described above, magnets located on one side of the rotor can undergo more degaussing than magnets located on the other side of the rotor. May be degaussed more quickly.

The dimensions and types of electrical machinery and potential issues described herein are not limited to generators for direct drive applications, nor are they limited to the field of wind turbines. Electrical machinery of considerable size that can suffer the same problems and / or have the same complexity may also be found, for example, in steam turbines and hydraulic turbines.

The present disclosure provides examples of systems and methods that at least partially solve some of the aforementioned shortcomings.

In the first aspect, the rotor for an electromechanical machine comprises a first type of permanent magnet and a second type of permanent magnet. The first and second types of permanent magnets have the same magnetic strength, the first type of permanent magnets have the first temperature rating, and the second type of permanent magnets have the first temperature rating. It has a different second temperature rating.

According to this aspect, a permanent magnet rotor that can cause a non-uniform temperature distribution along the rotor is provided. Degaussing of permanent magnets can occur, for example, when a fault current occurs. To avoid degaussing, a permanent magnet of "grade" (a combination of strength and temperature rating) that is high enough to avoid degaussing even when the magnet is at maximum temperature is usually selected. However, high grade magnets are more expensive than low grade magnets. A known solution is to increase the cooling of the permanent magnet rotor, thereby degrading the magnet. However, according to the aforementioned embodiments, different grades of magnets can be used in different regions of different temperatures, thereby providing a cost effective solution.

Throughout the present disclosure, different temperature ratings mean different intrinsic coercive forces. Coercive or magnetic coercive force is a measure of the ability of a ferromagnetic material to withstand an external magnetic field without degaussing. Coercive force is usually measured in oersted or ampere / meter units and is expressed as _HC . The larger value is the intrinsic coercive force _HCi , which considers only the magnetization and does not consider the contribution of the negative vacuum permittivity to the magnetic field B.

Throughout the present disclosure, the strength of a permanent magnet can be considered as its magnetic persistence. Persistent or residual magnetization or residual magnetism is the magnetization that remains in the ferromagnetic material when the external magnetic field is removed. The same magnetic persistence or the same magnetic strength as used throughout this disclosure means that the difference in magnetic persistence between one magnet and another is less than 10%, specifically less than 5%. It shall mean.

In a further aspect, a method is provided that comprises a step of determining the magnetic persistence of the permanent magnet of the permanent magnet rotor of an electromechanical machine and a step of determining the temperature distribution of the permanent magnet rotor in operation. The method then comprises determining a first area of the permanent magnet rotor with a higher average temperature and a second area of the permanent magnet rotor having a lower average temperature. Next, a first type magnet for the first area and a second type magnet for the second area are selected, the second type being different from the first type.

Non-limiting examples of the present disclosure are described below with reference to the accompanying drawings.

It is a perspective view of the wind turbine by an example. It is a detailed internal view of a nacelle of a wind turbine by an example. It is a figure which shows schematic sectional drawing of an example of an electric machine. It is a figure which shows roughly the degaussing curve. It is a figure which shows roughly the degaussing curve. It is a figure which shows two examples of a permanent magnet module schematically. It is a figure which shows two examples of a permanent magnet module schematically. It is a figure schematically showing an example of the method for selecting a permanent magnet suitable for a rotor of an electric machine.

In these figures, the same reference numerals are used to indicate matching elements.

FIG. 1 shows a perspective view of an example of a wind turbine 160. As shown, the wind turbine 160 includes a tower 170 extending from a support surface 150, a nacelle 161 mounted on the tower 170, and a rotor 115 coupled to the nacelle 161. The rotor 115 includes a rotatable hub 110 and at least one rotor blade 120 coupled to the hub 110 and extending outward from the hub 110. For example, in the illustrated embodiment, the rotor 115 includes three rotor blades 120. However, in an alternative embodiment, the rotor 115 may include more or less than three rotor blades 120. Each rotor blade 120 is spaced around the hub 110 so that the rotation of the rotor 115 is facilitated and the kinetic energy from the wind can be converted into available mechanical energy followed by electrical energy. Can be done. For example, the hub 110 can be rotatably coupled to a generator 162 (FIG. 2) positioned within the nacelle 161 to allow the generation of electrical energy.

FIG. 2 shows a simplified internal view of an example of the nacelle 161 of the wind turbine 160 of FIG. As shown, the generator 162 may be disposed within the nacelle 161. In general, the generator 162 may be coupled to the rotor 115 of the wind turbine 160 in order to generate electric power from the rotational energy generated by the rotor 115. For example, the rotor 115 can include a main rotor shaft 163 coupled to the hub 110 to rotate with the hub 110. The generator 162 may then be coupled to the rotor shaft 163 so that the rotation of the rotor shaft 163 drives the generator 162. For example, in the illustrated embodiment, the generator 162 includes a generator shaft 166 rotatably coupled to a rotor shaft 163 via a gearbox 164.

It should be appreciated that the rotor shaft 163, gearbox 164, and generator 162 may generally be supported within the nacelle 161 by a support frame or bed plate 165 positioned at the top of the wind turbine tower 170.

The nacelle 161 is rotatably coupled to the tower 170 by the yaw system 20 so that the nacelle 161 can rotate around the yaw axis YA. The yaw system 20 comprises yaw bearings having two bearing components configured to rotate relative to the other. The tower 170 is coupled to one of the bearing components and the bed plate or support frame 165 of the nacelle 161 is coupled to the other bearing component. The yaw system 20 includes an annular gear 21, a plurality of yaw drive devices 22 having a motor 23, a gearbox 24, and a pinion 25 for engaging the annular gear 21 so as to rotate one of the bearing components with respect to the other. And.

The blade 120 is coupled to the hub 110 via a pitch bearing 100 between the blade 120 and the hub 110. The pitch bearing 100 includes an inner ring and an outer ring. The wind turbine blade can be attached to either the inner or outer bearing ring and the hub is connected to the other. The blade 120 can rotate relative to the hub 110 when the pitch system 107 is activated. Therefore, the inner bearing ring can rotate with respect to the outer bearing ring. The pitch system 107 of FIG. 2 includes a pinion 108 that meshes with an annular gear 109 provided on the inner bearing ring to rotate the wind turbine blades around the pitch axis PA.

The energy generated by the generator can be delivered to a converter that adapts the output power of the generator to the requirements of the power grid. The electromechanical machine can include an electrical phase, eg, three electrical phases. The converter may be located inside the nacelle, inside the tower, or outside.

FIG. 3 schematically shows an electric machine. The electric machine may be a generator, specifically a directly driven wind turbine generator.

The generator 10 of FIG. 3 has a rotor 20, a stator 30, and a rotor 20 and a stator 30 that extend from the first side 101 to the second side 102 and are configured to rotate about a rotation shaft 33. It is provided with an air gap 40 between them.

The stator 30 in this figure includes a plurality of electric coils 90 and a stator structure 50 having a circumferential support 60 that supports the plurality of electric coils 90. The stator structure 50 extends from the first side 31 to the second side 32 along the rotation shaft 33 of the generator.

The generator 10 of FIG. 3 further includes an air cooling system 110 for cooling a plurality of electric coils 90. In this example, the air cooling system 110 comprises an electromechanical air inlet 111, an air distribution channel extending through a portion of the circumferential support 60, and an electromechanical air outlet 112 for fluid communication with the air gap 40. .. The electromechanical air inlet may allow airflow to enter the electromechanical machine.

The cooling air delivered by the air cooling system 110 can provide cold air to the air gap 40. Thereby, this air can cool the magnet 21 arranged in the rotor 20 together with the electromagnetic element arranged along the air gap, for example, the electric coil 90 arranged in the stator.

The air distribution channel of this example comprises an air entrance 71 that communicates fluid with the electromechanical air inlet 111 and is located on the first side 31 of the circumferential support 60. A plurality of air distribution channels are arranged on the second side 32 of the circumferential support 60 for fluid communication with the air gap 40 in order to distribute the air flow from the electromechanical air inlet 111 along the air gap 40. The axial air opening 73 is further provided.

In the generator 10 of this particular example, the rotor 20 surrounds the stator 30. The rotor is rotatably mounted on the support frame 9 of the wind turbine via the generator bearing 11. The rotor 20 can be connected to the rotor hub of a wind turbine (not shown in this figure) to rotate the rotor hub. The stator 30 can be firmly connected to the support frame 9 of the wind turbine. The electrical winding 90 may be located outside the outer rim of the circumferential support and the magnet or magnet module 21 may be located inside the outer rotor rim 22.

In the example of this figure, the generator comprises a cover plate 12 located on the first side 101. The cover plate 12 can close the generator and can be fixedly attached to the support frame 9 of the wind turbine. The sealing member may be arranged between the portion of the rotor rim 22 near the first side 101 and the cover plate 12.

In another example, the cover plate 12 may form part of the rotor 20. In some of these examples, additional generator bearings can rotatably connect the cover plate to the support frame of the wind turbine. In another example, the rotor 20 may be inside the stator in the radial direction, i.e., the stator 30 may surround the rotor 20 in the radial direction. The rotor 20 may be coupled directly to the wind turbine rotor (eg, to the rotor shaft or rotor hub), or a gearbox may be located between the wind turbine rotor and the generator.

The cold air flow can enter the generator 10 through the electromechanical air inlet 111. This low temperature air flow can be guided toward the air gap 40 of the generator 10 through the stator structure 50 and the plurality of axial air openings 73. Therefore, the air flow can be distributed substantially uniformly along the circumference of the air gap 40. Therefore, this cold air flow can cool the electromagnetic components of the rotor and stator arranged in the air gap 40. The air flow can axially pass through the air gap from the second side 102 to the first side 101 to cool the electromagnetic components located in the air gap. The heat from the electromagnetic component is transferred to the air flow, and the temperature of the air flow on the first side 101 may be higher than the air flow on the second side 102. This hot air stream may then exit the generator through the electromechanical air outlet 112 and be cooled in the heat exchanger. The electromechanical air outlet may also allow an air flow to exit the electromechanical machine.

Thus, the electromagnetic components located in the air gap, such as magnets, can operate at temperatures within a predetermined suitable range, and thus the electromechanical machine can operate efficiently.

The air cooling system according to this figure comprises a second side radial air channel 114 extending radially between the second side 32 of the circumferential support 60 and the second side 102 of the rotor 20. The radial air channel 114 on the second side allows the plurality of axial air openings 73 to communicate with the air gap 40.

The air cooling system may include a first side radial air channel 113 extending radially between the first side 31 of the circumferential support 60 and the first side 101 of the rotor 20. The radial air channel 113 on the first side allows the air gap 40 to communicate with the electromechanical air outlet 112.

In some examples, the cooling system may include a heat exchanger. The heat exchanger can include a first fluid circuit and a second fluid circuit. The first fluid circuit may be connected to a cooling system to cool the electrical machine. The second fluid circuit can cool the fluid flowing along the first fluid circuit. The fluid in the second fluid circuit can be, for example, air or water. The first fluid circuit may include a heat exchanger air inlet connected to an electromechanical air outlet to receive warm airflow from the air gap. In addition, the first fluid circuit may include a heat exchanger air outlet connected to an electromechanical air inlet to deliver airflow to the air gap. A conduit can be placed between the electromechanical air outlet and the heat exchanger air inlet to direct the air flow towards the heat exchanger. The conduit can connect the heat exchanger air outlet to the electromechanical air inlet.

The air flow from the air gap can be cooled by a second fluid circuit, and this cooled air flow is introduced into the electromechanical machine through the electromechanical air inlet and is an electromagnetic component placed in the air gap. Can be cooled.

As mentioned above, the cold airflow can therefore cool the electromagnetic components of the rotor and stator located in the air gap 40. The air flow can axially pass through the air gap from the second side 102 to the first side 101 to cool the electromagnetic components located in the air gap. The heat from the electromagnetic component is transferred to the air flow, and the temperature of the air flow on the first side 101 may be higher than the air flow on the second side 102. Cooling of the magnets on this side of the electromechanical machine is done with warmer air, as the temperature of the (cooling) airflow may be higher on the first side 101. Therefore, cooling may be locally less effective.

Therefore, the magnet 21 on the high temperature side may operate at a higher temperature than the magnet on the cooler side of the rotor.

FIG. 4A shows a degaussing curve 205 of a permanent magnet, specifically a neodymium iron boron magnet. The degaussing curve 205 is a "normal" degaussing curve, but the "unique" degaussing curve 200 is shown for the same magnet.

The degaussing curve shows the behavior of the magnet for a given temperature and how degaussing can occur in the presence of a particular magnetic field. The degaussing curve 205 usually indicates a knee point 208. As long as the magnetic field is within the linear area 207 of the curve, the properties of the magnet will return to their original strength. However, if the magnetic field is above knee point 208, in the absence of the magnetic field, the magnet will not return to its original strength, i.e., its original magnetic persistence. Rather, the line 209 shows how the magnet returns to the lower residual magnetism, i.e., the magnet is partially degaussed.

A high magnetic field that can be partially or completely demagnetized can be caused, for example, by an electrical failure of the generator.

For different temperatures, there are different degaussing curves for a given magnet. At higher temperatures, the knee point is reached with a lower magnetic field, i.e. demagnetization occurs more easily.

FIG. 4B schematically shows the degaussing curves 205, 207 of two types of permanent neodymium magnets having the same intensity, ie, the same magnetic persistence.

However, magnets have different temperature ratings, i.e. different intrinsic coercive forces. Curve 207 (and curve 202) is the degaussing curve of the permanent magnet N48SH with a higher temperature rating, and curve 205 (and curve 200) is the degaussing curve of the permanent magnet N48H with a lower temperature rating.

Degaussing curves 205 and 207 indicate degaussing for a temperature of 80 ° C. Irreversible degaussing of the permanent magnet N48SH has been shown to occur at higher magnetic fields.

As an aspect of the present disclosure (see FIG. 3), a rotor 20 for an electric machine 10 comprising a first type permanent magnet and a second type permanent magnet is provided. The first and second types of permanent magnets have the same magnetic strength, the first type of permanent magnets have the first temperature rating, and the second type of permanent magnets have the first temperature rating. It has a different second temperature rating.

In the example of FIG. 3, the electromechanical machine can include a first set of permanent magnets (of the first type) and a second set of permanent magnets (of the second type). That is, different individual magnets can be used. In another example, the magnetic material may be provided using additive manufacturing. In such cases, fluctuations in magnet grade (especially temperature rating) may be more continuous.

The permanent magnet may be made of a rare earth material, and specifically, a neodymium iron-boron magnet may be used. In an alternative example, the permanent magnets are, for example, a family of iron alloys consisting of ceramic materials, samarium cobalt, or alnico (alnico is a family of iron alloys consisting primarily of aluminum (Al), nickel (Ni), and cobalt (Co) in addition to iron. Is made from).

In the example, the rotor 20 can have a radial rotor rim, extending axially from the first end 102 to the second end 101, and the first set of permanent magnets is in the first area of the rotor. Arranged, the second set of permanent magnets is located in the second area of the rotor, the first area is closer to the first end 102 than the second area.

The rotor of this example is configured such that the first end 102 is located in the electrical machine 10 so that it is closer to the cooling air supply 73 than the second end 101.

In some examples, the rotor may further include a third set of permanent magnets, the third set of permanent magnets having the same magnetic strength and different from the first and second temperature ratings. It has a third temperature rating. In these examples, three different temperature zones can be defined and the appropriate permanent magnets can be selected for each of these zones. In a further example, different sets of four, five or more permanent magnets can be provided.

In examples where the magnetic material is provided using 3D printing or additive manufacturing, a specific number of magnet types (temperature ratings) can be provided, or continuous changes in temperature ratings can be provided.

In a further aspect, an electrical machine 10 with such a rotor is provided. The electric machine 10 may be a generator. In yet another embodiment, the wind turbine 160 comprises a tower 170, a nacelle 161 rotatably attached to the tower 170, and a wind turbine rotor 115 including a plurality of blades 120, wherein the wind turbine rotor 115 is of a generator. Operately connected to the rotor, the rotor is the rotor described herein.

5A and 5B schematically show two examples of permanent magnet modules for rotors of electrical machinery. FIG. 5A shows an example of a permanent magnet module 220 having a base 225. The base can be attached to the rotor rim. The base can be attached, for example, using T-shaped anchors that fit inside the recesses on both sides of the base 225. A plurality of permanent magnets 230 can be arranged on top of the base 225.

The permanent magnet module 220 in this example can have the same length as the rotor, i.e., the permanent magnet module extends from the first (front) side of the rotor to the second (rear) side of the rotor. The first side 232 of the rotor (and the permanent magnet module 220) may be on the low temperature side and the second side 234 may be on the high temperature side. During operation, the average temperature of the magnets on the low temperature side 232 may be lower than the average temperature on the high temperature side.

A first area 240 with a lower average temperature may be defined, or a second area 242 with a higher average temperature may be defined. The magnet 230 in the first area 240 may be different from the magnet 230 in the second area 242.

Provided is an electromechanical machine having a rotor with a plurality of permanent magnets, a stator with a plurality of electric coils, and a radial air gap between the rotor and the stator. The plurality of permanent magnets includes a first group of magnets and a second group of magnets, the first group of magnets has a first intrinsic coercive force, and the second group of magnets has a different second group. Has an inherent coercive force of. The first group of magnets may be located in the first zone 240 and the second group of magnets may be located in the second zone 242.

In the example, the first and second groups of magnets have the same magnetic persistence.

In some examples, the electromechanical machine may further include a cooling supply for supplying cooling air to the radial air gap, where the magnets in the first group provide more cooling than the magnets in the second group. Close to the club. The first intrinsic coercive force may be lower than the second intrinsic coercive force.

In some examples, the rotor comprises a rotor rim and a plurality of permanent magnet modules attached to the rotor rim.

In some examples, the plurality of permanent magnet modules include a first group of permanent magnet modules and a second group of permanent magnet modules, and a first group of permanent magnet modules contains a first group of magnets. The second group of permanent magnet modules includes the second group of magnets. The magnet module does not necessarily have the same axial length as the rotor. In the example, the two magnet modules may be arranged axially back and forth with each other. One magnet module may have a first group of magnets and the other magnet module may have a second group of magnets.

FIG. 5B schematically shows another example of the permanent magnet module 250. The permanent magnet module 250 has a substantially V-shaped magnet portion in an axial cross section. The permanent magnet module 250 for an electromechanical machine extends along the axial direction. As mentioned above, the temperature distribution may be non-uniform in the axial direction. The low temperature side 282 and the high temperature side 284 may be present.

Module 250 comprises a permanent magnet assembly comprising at least one permanent magnet and a base 255 supporting at least a portion of the permanent magnet assembly. The base extends radially (along lines AA) from the bottom adapted to be positioned on the rotor of the electromechanical machine (not shown) to the top. The permanent magnet assembly has a first tilted permanent magnet portion 261 (V-shaped "first leg") and a second tilted outwardly along the radial direction (along line AA). A tangential permanent magnet portion 262 (V-shaped "second leg") and a tangential permanent magnet portion 263 arranged parallel to the tangential direction (along the line BB). The direction is substantially perpendicular to the radial direction.

In the example of FIG. 5B, the permanent magnet assembly has a first tilted permanent magnet portion 261 with a first permanent magnet, a second tilted permanent magnet portion 262 with a second permanent magnet, and a third permanent magnet. Includes a tangential permanent magnet portion 263 and the like. In addition, the permanent magnet modules include several first permanent magnets 261 arranged axially in a row, or second permanent magnets 262 arranged axially in a row, or axially in a row. A third permanent magnet 263 may be provided along the line. Specifically, the axial lengths of these magnets may be similar.

Some permanent magnet modules may be arranged axially side by side with each other so as to cover the axial length of the electromechanical machine.

In the example of FIG. 5B, the permanent magnet module 250 further comprises a base that supports the permanent magnet at least partially and extends radially from the bottom to the top adapted to be positioned on the rotor of the electromechanical machine. , The first permanent magnet 261 and the second permanent magnet 262 are arranged so as to be inclined outward along the radial direction, and the third permanent magnet 263 is arranged substantially parallel to the tangential direction. Is substantially perpendicular to the radial direction.

The first and second permanent magnets may be substantially rectangular in axial cross section. Alternatively or additionally, the first permanent magnet 261 and the second permanent magnet 262 may have a substantially trapezoidal cross section. In this way, the fixation of the magnet to the base is improved and therefore the risk of accidental detachment of such magnets can be reduced.

Additionally, the third permanent magnet 263 may have a rectangular cross section. In another example, the third permanent magnet 263 may have a rectangular cross section with tilted edges.

The example of FIG. 5B shows a base 255 comprising an upper pole piece 273, a first lateral wing 270, and a second lateral wing 272. The permanent magnet assembly may be placed between the upper magnetic pole piece 273 and the first lateral wing 270 and the second lateral wing 272. In this example, the upper magnetic pole piece 273 has a substantially trapezoidal axial cross section with a long side parallel to the short side and a first side and a second side connecting the long side to the short side. Have. In this example, the third permanent magnet 263 is attached to the short side of the upper magnetic pole piece, the first permanent magnet 261 is attached to the first side side of the upper magnetic pole piece, and the second permanent magnet portion 262 is the upper part. It is attached to the second side of the magnetic pole piece.

In this example, the first lateral wing 261 and the second lateral wing 262 have a substantially right triangle cross section.

As in the example of FIG. 5A, the base may further include lateral recesses extending along the axial direction. A well-formed anchor can engage the shape of such lateral recesses and can then be used to secure the permanent magnet module to the rotor rim.

In some examples, the base may include a cooling channel 279 for cooling the magnet in order to avoid overheating of the magnet, which reduces the efficiency of the electromechanical machine.

The low temperature side 282 and the high temperature side 284 may be present. The magnets 261, 262, and 263 may change along the axial direction. The cooler area 290 of the permanent magnet module can have a lower "grade" magnet and the hotter area 292 can have a higher "grade" magnet. Specifically, the strength of the magnets may be the same, but the temperature rating may be higher for the magnets in the hotter area 292.

In some examples, one or more permanent magnet modules include a first type of magnet and a second type of magnet. The magnet type in the permanent magnet module can be changed in the axial direction as described above.

In particular, referring to the example of FIG. 5B, the permanent magnet module includes one or more tilting magnets 261 and 262 tilted in the radial direction and one or more tilted magnets arranged perpendicular to the radial direction. Including the tangential magnet 263, the tilting magnets 261 and 262 can be the first type magnet, and the tangential magnet 263 can be the second type magnet.

In this example, the tilt magnet can have a lower temperature rating than the horizontal magnet. During operation, the temperatures of the various magnets in the axial plane may actually be very uniform, i.e., there may be little difference in temperature within the magnets in the same axial plane. However, in the arrangement shown in FIG. 5B, the magnetic field of the tangential magnet 263 may be stronger than that of the tilt magnet. For example, a magnetic field that can be degaussed in the event of an electrical failure can more easily degauss the tangential magnet 263 than the tilting magnets 261 and 262. Therefore, the temperature rating or intrinsic coercive force of the tangential magnet 263 can be selected to be higher than that of the tilting magnet.

The first type magnet may have a lower temperature rating such as N48H, and the second type magnet in these examples may be, for example, N48SH.

It is also possible to combine both axial magnet type variation and differentiation within the permanent magnet module.

FIG. 6 schematically shows an example of a method 300 for selecting a magnet for a permanent magnet rotor of an electric machine. The method comprises step 310 of determining the magnetic persistence of a permanent magnet. Depending on the nominal power of the generator, the number and size of magnets, etc., the appropriate strength of the permanent magnets can be determined. All magnets in a permanent magnet rotor can have the same strength.

The method further comprises step 330 to determine the temperature distribution of the permanent magnet rotor in operation. The step of determining the temperature distribution can include step 320 of simulating the operation of an electromechanical machine.

The method further comprises a step 340 of determining a first area of the permanent magnet rotor with a lower average temperature and determining a second area of the permanent magnet rotor with a higher average temperature. Two or more areas of the permanent magnet rotor can be defined based on the temperature distribution. In some examples, the first area has an average temperature 10-40 ° C higher than the second area.

The method of this example further comprises selecting a first type magnet for the first area and selecting a second type magnet for the second area, the second type being the first type. Different from type.

In some examples, the first type magnet may have a lower temperature rating than the second type magnet because the first area has a lower average temperature during operation. This may occur, for example, if the first area is located near the cooling air supply section.

In some examples, only the first type or the second type of magnets are selected. That is, only two temperature zones are defined. In many embodiments, it has been found that two temperature ranges are sufficient to optimize costs and avoid degaussing.

The present specification discloses the present invention including preferred embodiments using examples, and one of ordinary skill in the art can make and use any device or system to carry out any incorporated method. Including, it makes it possible to practice the present invention. The patentable scope of the invention is defined by the claims and may include other embodiments conceived by those skilled in the art. Such other embodiments are patented if they have structural elements that are not significantly different from the wording of the claims, or if they contain equivalent structural elements that are not substantially different from the wording of the claims. It is intended to be within the scope of the claim. Further embodiments according to the principles of the present application and those skilled in the art can be adapted by mixing and adapting embodiments from the various embodiments described above as well as other known equivalents for each such embodiment. Technology can be built. If the reference codes associated with the drawings are placed within the brackets of the claims, those reference codes are merely to enhance the clarity of the claims and limit the scope of the claims. Should not be interpreted as.

9 Support frame 10 Electric machine, Generator 11 Generator bearing 12 Cover plate 20 Rotor, Yaw system 21 Magnet, Magnet module, Circular gear 22 Rotor rim, Yaw drive 25 Pinion 30 Stator 31 First side 32 Second side 33 Rotating shaft 40 Air gap 50 Stator structure 60 Circumferential support 71 Air entrance 73 Cooling air supply section, axial air opening 90 Electric coil, electric winding 100 Pitch bearing 101 First side, second end 102 Second side, first end 107 Pitch system 108 Pinion 109 Circular gear 110 Hub, Air cooling system 111 Electromechanical air inlet 112 Electromechanical air outlet 113 First side radial air channel 114 Second side Radial Air Channel 115 Rotor 120 Rotor Blade 160 Wind Turbine 161 Nasser 162 Generator 163 Rotor Shaft, Main Rotor Shaft 164 Gearbox 165 Support Frame, Bed Plate 170 Tower 200 Demagnetizing Curve 202 Demagnetizing Curve 205 Demagnetizing Curve 207 Demagnetizing Curve, Linear Area 208 Knee Point 220 Permanent Magnet Module 225 Base 230 Magnet 232 First Side, Cold Side 240 First Area 242 Second Area 250 Permanent Magnet Module 255 Base 261 Permanent Magnet, Tilt Permanent Magnet Part, First Permanent Magnet, 1st side wing 262 tilting magnet, tilting permanent magnet part, 2nd permanent magnet, 2nd permanent magnet part, 2nd side wing 263 tangential direction magnet, 3rd permanent magnet, tangential direction permanent magnet part 270 First side wing 272 Second side wing 273 Upper pole piece 279 Cooling channel 282 Cold side 284 Hot side 290 Colder area 292 Hotter area 300 Method PA Pitch axis YA Yaw axis

Claims (15)

A rotor (20) for an electric machine (10) comprising a first type permanent magnet and a second type permanent magnet.
The first type permanent magnet and the second type permanent magnet have the same magnetic strength.
The first type of permanent magnet has a first temperature rating, and the second type of permanent magnet has a second temperature rating different from the first temperature rating, for an electric machine (10). Rotor (20). The rotor (20) according to claim 1, wherein the permanent magnet is made of a rare earth material, and specifically, the permanent magnet is a neodymium iron boron magnet. The rotor (20) extends axially from the first end (102) to the second end (101).
A first set of permanent magnets is placed in the first area of the rotor (20).
A second set of permanent magnets is placed in the second area of the rotor (20).
The rotor (20) according to claim 1 or 2, wherein the first area is closer to the first end (102) than the second area. Claimed to be configured to be arranged in the electrical machine (10) so that the first end (102) is closer to the cooling air supply (73) than the second end (101). Item 3. The rotor (20) according to Item 3. A third set of permanent magnets is further provided, wherein the third set of permanent magnets has the same magnetic strength and a third temperature rating different from the first and second temperature ratings. The rotor (20) according to any one of items 1 to 4. The rotor (20) according to any one of claims 1 to 5, comprising a rotor rim (22) and a plurality of permanent magnet modules (220, 250) attached to the rotor rim (22). The plurality of permanent magnet modules (220, 250) include a first group of permanent magnet modules and a second group of permanent magnet modules.
The rotor (20) according to claim 6, wherein the permanent magnet module of the first group comprises a magnet of the first type, and the permanent magnet module of the second group comprises a magnet of the second type. 20. The rotor (20) of claim 6, wherein one or more of the permanent magnet modules (220, 250) comprises the first type magnet and the second type magnet or magnet portion. ). The permanent magnet module (220, 250) includes one or a plurality of tilting magnets (261, 262) arranged at an angle with respect to the radial direction, and one or a plurality of inclined magnets (261, 262) arranged at an angle with respect to the radial direction. Including multiple tangential magnets (263)
The rotor (20) according to claim 8, wherein the tilting magnets (261 and 262) are the first type magnets, and the tangential direction magnets (263) are the second type magnets. The electric machine (10) including the rotor (20) according to any one of claims 1 to 9, wherein the electric machine (10) is optionally a generator (162). Electrical machine (10). A tower (170), a nacelle (161) rotatably attached to the tower (170), a wind turbine rotor (115) including a plurality of blades (120), and a generator (162) according to claim 10. ), And optionally, the wind turbine (160) in which the generator (162) is a direct drive type. The step (310) of determining the magnetic persistence of the permanent magnet of the permanent magnet rotor of the electric machine (10),
Step (330) to determine the temperature distribution of the permanent magnet rotor in operation,
A step (340) of determining a first area of the permanent magnet rotor having a lower average temperature and determining a second area of the permanent magnet rotor having a higher average temperature.
A step of selecting a first type of magnet for the first area and selecting a second type of magnet for the second area, wherein the second type is the first type. A method (300) that includes steps (350) and selections that are different from the type. 12. The method (300) of claim 12, wherein the first type magnet has a lower temperature rating than the second type magnet. 12. The method (300) of claim 12, wherein the step of determining the temperature distribution of the permanent magnet rotor in operation comprises the step (320) of simulating the operation of the electromechanical machine (10). .. The method (300) according to any one of claims 12 to 14, wherein the first type magnet and the second type magnet are provided by additive manufacturing.

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